1. Technical Field
The present invention relates generally to an illuminating system, and more particularly to a dimmable LED illuminating system.
2. Description of Related Art
Fluorescent lamp is the commonest device for indoor lighting. In order to provide a room with different luminance, a conventional method is to light fluorescent lamps with different numbers. It is because that the fluorescent lamps can be turned on and off only; in other words, there is no intermediate status in between. Sometimes, it provides an uneven brightness in the room when specified fluorescent lamps are off. Furthermore, only a few grades of luminance can be selected because there are only a few combinations of the specific fluorescent lamps to be on and off.
In present days, more and more fluorescent lamps are replaced by LED (light emitting diode) lamps, which have significantly better energy conversion efficiency than the fluorescent lamps. In the field of LED lamps, how to make the LED lamp provide a stable and constant luminance even while the input voltage is changing is an important issue in design of the driver of the LED lamp. Therefore, we are trying to design a LED lamp which is dimmable with a new circuit design.